Citigroup Inc. more than doubled its Asian and European natural gas forecasts for next quarter. : (Bloomberg) -- Citigroup Inc. more than doubled its Asian and European natural gas forecasts for next quarter and said prices could surge to as high as $100 per million British thermal units in the event of a particularly cold winter. Liquefied natural gas prices are skyrocketing as seasonally low European inventories, booming Chinese demand and supply constraints from Russia to Nigeria lead to a bidding war for the power generation feedstock before the northern hemisphere winter.